I have just found out I'm pregnant

Gaelyn • Rainbow baby Stevie Grace born Feb ‘18 after 3 losses. TTC number 2. Wife of Chris. Stepmom of Zoe (13) Pitbull mom. Lover of rainbows, sunsets, summer, adventure.
I have just found out I'm pregnant! It's my 4th pregnancy after 3 miscarriages so obviously terrifying. It's made even more complicated by the fact that I had major surgery on my leg and foot a month ago and have been on hectic meds. (We were usingGlow to track ovulation and took 10 days off during my fertile window, so don't know how this happened! I am 5 days late, and a HPK showed a verrry faint line (not my FMU.) So because I'm on serious meds I went to get bloods done asap and my beta is only 20, which means either a pregnancy that won't stick or I'm literally just a few days pregnant! Dr wants me to start on Clexane, progesterone and a specific folic acid tonight. And I must redo the beta after 48 hours on Saturday. She will only get those results on Monday though. Argh a whole weekend of waiting! So it's possible this is a chemical pregnancy, where the pregnancy is not going to stick and that's why the levels are low. Or it's just that I ovulated late and this it's just super new. I also have to stop the pain meds which terrifies me as I'm still in a LOT of pain every day.
​Does anyone have experience of a super low beta - did it turn out to be a chemical? Or did you just test really early on and that's why it's low? I don't want to get my hopes up for nothing so any input is much appreciated!